Investigation of some Intrinsic Properties of Thermal Sprayed Molybdenum Coatings for Railway Axle Applications

Abstract

Thermal sprayed Mo coatings deposited on steel support deposited by electric arc and atmospheric plasma spray were investigated. Microstructural investigation of the coatings showed that in both variants the splats formed by rapid solidification and splashing during the impact with the substrate have irregular shape, exhibit cracks and scattered debris. The measured average equivalent diameter of the splats and the calculated average diameter of the particles that generated the splats are higher for electric arc spraying. Using the measured and calculated data it was descibed the relathionship between splats diameter, splats thickness and flattening degree. Some intrinsec properties of the coatings as roughness, hardness and bond strength were measured. All these properties are influenced by the splat size. Lower size of the splats lead to reduced surface roughness, higher hardness and higher bond strength of the coatings.